Hi I'm just trying to get my head around some of the tables in bs7671. Can anyone help me with an example of what type of cable TABLE 4D2A – Multicore 70 °C thermoplastic insulated and thermoplastic sheathed cables, non-armoured (COPPER CONDUCTORS) might be. All the others I know types and utilisations for them but this one I just can't seem to fathom what type of cable it's for.... Thanks
Its also quite a good one to use for any 'probably PVC' plastic round cables that you come across - so CY SY NJJ etc.
It errs on the safe side of course if the plastic is really OK to 90C, but there is a lot of latitude for using figures from the 'wrong' table for a cable that is not listed but similar once you know how to do so. For obvious reasons the regs cannot handle all cables in all possible mounting configurations so some whistling through teeth and scientific green fingering is sometimes needed.
4D2A is for all ordinary PVC/PVC cables (flexes are slightly different and need additional factors or just use their own tables, 4F1). Traditionally 4D2 was for all shapes of cables, but some "flat" types (i.e. T&E) now have their own table 4D5 which gives slightly higher ratings for some installation methods) - so 4D2 now is mostly for round cables plus flat ones where the installation method isn't covered by 4D5.
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